From: Adhemerval Zanella Date: Wed, 30 Oct 2019 18:56:39 +0000 (-0300) Subject: nptl: Replace non cancellable pause/nanosleep with futex X-Git-Tag: glibc-2.31~306 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=215078017fd25fd64074e25ccd3dde0f6f19d4fe;p=thirdparty%2Fglibc.git nptl: Replace non cancellable pause/nanosleep with futex To help y2038 work avoid duplicate all the logic of nanosleep on non cancellable version, the patch replace it with a new futex operation, lll_timedwait. The changes are: - Add a expected value for __lll_clocklock_wait, so it can be used to wait for generic values. - Remove its internal atomic operation and move the logic to __lll_clocklock. It makes __lll_clocklock_wait even more generic and __lll_clocklock slight faster on fast-path (since it won't require a function call anymore). - Add lll_timedwait, which uses __lll_clocklock_wait, to replace both __pause_nocancel and __nanosleep_nocancel. It also allows remove the sparc32 __lll_clocklock_wait implementation (since it is similar to the generic one). Checked on x86_64-linux-gnu, sparcv9-linux-gnu, and i686-linux-gnu. Reviewed-by: Carlos O'Donell --- diff --git a/nptl/lll_timedlock_wait.c b/nptl/lll_timedlock_wait.c index cd3cc3d3715..952b042555b 100644 --- a/nptl/lll_timedlock_wait.c +++ b/nptl/lll_timedlock_wait.c @@ -25,39 +25,38 @@ int -__lll_clocklock_wait (int *futex, clockid_t clockid, +__lll_clocklock_wait (int *futex, int val, clockid_t clockid, const struct timespec *abstime, int private) { - /* Reject invalid timeouts. */ - if (! valid_nanoseconds (abstime->tv_nsec)) - return EINVAL; + struct timespec ts, *tsp = NULL; - /* Try locking. */ - while (atomic_exchange_acq (futex, 2) != 0) + if (abstime != NULL) { - struct timespec ts; + /* Reject invalid timeouts. */ + if (! valid_nanoseconds (abstime->tv_nsec)) + return EINVAL; - /* Get the current time. This can only fail if clockid is not - valid. */ + /* Get the current time. This can only fail if clockid is not valid. */ if (__glibc_unlikely (__clock_gettime (clockid, &ts) != 0)) return EINVAL; /* Compute relative timeout. */ - struct timespec rt; - rt.tv_sec = abstime->tv_sec - ts.tv_sec; - rt.tv_nsec = abstime->tv_nsec - ts.tv_nsec; - if (rt.tv_nsec < 0) + ts.tv_sec = abstime->tv_sec - ts.tv_sec; + ts.tv_nsec = abstime->tv_nsec - ts.tv_nsec; + if (ts.tv_nsec < 0) { - rt.tv_nsec += 1000000000; - --rt.tv_sec; + ts.tv_nsec += 1000000000; + --ts.tv_sec; } - if (rt.tv_sec < 0) + if (ts.tv_sec < 0) return ETIMEDOUT; - /* If *futex == 2, wait until woken or timeout. */ - lll_futex_timed_wait (futex, 2, &rt, private); + tsp = &ts; } + /* If *futex == val, wait until woken or timeout. */ + lll_futex_timed_wait (futex, val, tsp, private); + return 0; } diff --git a/nptl/pthread_mutex_lock.c b/nptl/pthread_mutex_lock.c index 0ab890d8158..ace436d5a6d 100644 --- a/nptl/pthread_mutex_lock.c +++ b/nptl/pthread_mutex_lock.c @@ -434,7 +434,8 @@ __pthread_mutex_lock_full (pthread_mutex_t *mutex) /* Delay the thread indefinitely. */ while (1) - __pause_nocancel (); + lll_timedwait (&(int){0}, 0, 0 /* ignored */, NULL, + private); } oldval = mutex->__data.__lock; diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c index d6f0d9e31a8..76b93bddc6d 100644 --- a/nptl/pthread_mutex_timedlock.c +++ b/nptl/pthread_mutex_timedlock.c @@ -401,22 +401,10 @@ __pthread_mutex_clocklock_common (pthread_mutex_t *mutex, /* Delay the thread until the timeout is reached. Then return ETIMEDOUT. */ - struct timespec reltime; - struct timespec now; - - INTERNAL_SYSCALL (clock_gettime, __err, 2, clockid, - &now); - reltime.tv_sec = abstime->tv_sec - now.tv_sec; - reltime.tv_nsec = abstime->tv_nsec - now.tv_nsec; - if (reltime.tv_nsec < 0) - { - reltime.tv_nsec += 1000000000; - --reltime.tv_sec; - } - if (reltime.tv_sec >= 0) - while (__nanosleep_nocancel (&reltime, &reltime) != 0) - continue; - + do + e = lll_timedwait (&(int){0}, 0, clockid, abstime, + private); + while (e != ETIMEDOUT); return ETIMEDOUT; } diff --git a/sysdeps/nptl/lowlevellock.h b/sysdeps/nptl/lowlevellock.h index e3f006537a3..92298f3b7ed 100644 --- a/sysdeps/nptl/lowlevellock.h +++ b/sysdeps/nptl/lowlevellock.h @@ -21,6 +21,7 @@ #include #include +#include /* Low-level locks use a combination of atomic operations (to acquire and release lock ownership) and futex operations (to block until the state @@ -121,10 +122,12 @@ extern void __lll_lock_wait (int *futex, int private) attribute_hidden; #define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private) -extern int __lll_clocklock_wait (int *futex, clockid_t, +extern int __lll_clocklock_wait (int *futex, int val, clockid_t, const struct timespec *, int private) attribute_hidden; +#define lll_timedwait(futex, val, clockid, abstime, private) \ + __lll_clocklock_wait (futex, val, clockid, abstime, private) /* As __lll_lock, but with an absolute timeout measured against the clock specified in CLOCKID. If the timeout occurs then return ETIMEDOUT. If @@ -136,7 +139,15 @@ extern int __lll_clocklock_wait (int *futex, clockid_t, \ if (__glibc_unlikely \ (atomic_compare_and_exchange_bool_acq (__futex, 1, 0))) \ - __val = __lll_clocklock_wait (__futex, clockid, abstime, private); \ + { \ + while (atomic_exchange_acq (futex, 2) != 0) \ + { \ + __val = __lll_clocklock_wait (__futex, 2, clockid, \ + abstime, private); \ + if (__val == EINVAL || __val == ETIMEDOUT) \ + break; \ + } \ + } \ __val; \ }) #define lll_clocklock(futex, clockid, abstime, private) \ diff --git a/sysdeps/sparc/sparc32/lll_timedlock_wait.c b/sysdeps/sparc/sparc32/lll_timedlock_wait.c deleted file mode 100644 index bd639a70911..00000000000 --- a/sysdeps/sparc/sparc32/lll_timedlock_wait.c +++ /dev/null @@ -1 +0,0 @@ -/* __lll_clocklock_wait is in lowlevellock.c. */ diff --git a/sysdeps/sparc/sparc32/lowlevellock.c b/sysdeps/sparc/sparc32/lowlevellock.c index 074ecf0636f..1a0ab4d9f23 100644 --- a/sysdeps/sparc/sparc32/lowlevellock.c +++ b/sysdeps/sparc/sparc32/lowlevellock.c @@ -50,46 +50,4 @@ __lll_lock_wait (int *futex, int private) } while (atomic_compare_and_exchange_val_24_acq (futex, 2, 0) != 0); } - - -int -__lll_clocklock_wait (int *futex, clockid_t clockid, - const struct timespec *abstime, int private) -{ - /* Reject invalid timeouts. */ - if (! valid_nanoseconds (abstime->tv_nsec)) - return EINVAL; - - do - { - struct timespec ts; - struct timespec rt; - - /* Get the current time. This can only fail if clockid is not - valid. */ - if (__glibc_unlikely (__clock_gettime (clockid, &ts) != 0)) - return EINVAL; - - /* Compute relative timeout. */ - rt.tv_sec = abstime->tv_sec - ts.tv_sec; - rt.tv_nsec = abstime->tv_nsec - ts.tv_nsec; - if (rt.tv_nsec < 0) - { - rt.tv_nsec += 1000000000; - --rt.tv_sec; - } - - /* Already timed out? */ - if (rt.tv_sec < 0) - return ETIMEDOUT; - - /* Wait. */ - int oldval = atomic_compare_and_exchange_val_24_acq (futex, 2, 1); - if (oldval != 0) - lll_futex_timed_wait (futex, 2, &rt, private); - } - while (atomic_compare_and_exchange_val_24_acq (futex, 2, 0) != 0); - - return 0; -} #endif diff --git a/sysdeps/unix/sysv/linux/sparc/lowlevellock.h b/sysdeps/unix/sysv/linux/sparc/lowlevellock.h index 34441f8ff56..6c005e8ffa8 100644 --- a/sysdeps/unix/sysv/linux/sparc/lowlevellock.h +++ b/sysdeps/unix/sysv/linux/sparc/lowlevellock.h @@ -24,6 +24,7 @@ #include #include #include +#include #include @@ -75,9 +76,13 @@ __lll_cond_lock (int *futex, int private) #define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private) -extern int __lll_clocklock_wait (int *futex, clockid_t, const struct timespec *, +extern int __lll_clocklock_wait (int *futex, clockid_t, int val, + const struct timespec *, int private) attribute_hidden; +#define lll_timedwait(futex, val, clockid, abstime, private) \ + __lll_clocklock_wait (futex, val, clockid, abstime, private) + static inline int __attribute__ ((always_inline)) __lll_clocklock (int *futex, clockid_t clockid, @@ -87,7 +92,20 @@ __lll_clocklock (int *futex, clockid_t clockid, int result = 0; if (__glibc_unlikely (val != 0)) - result = __lll_clocklock_wait (futex, clockid, abstime, private); + { + do + { + int oldval = atomic_compare_and_exchange_val_24_acq (futex, val, 1); + if (oldval != 0) + { + result = __lll_clocklock_wait (futex, 2, clockid, abstime, + private); + if (result == EINVAL || result == ETIMEDOUT) + break; + } + } + while (atomic_compare_and_exchange_val_24_acq (futex, val, 0) != 0); + } return result; } #define lll_clocklock(futex, clockid, abstime, private) \